Motor fuel composition



United. States Patent 3,098,727 MOTQR FUEL COMPOSITION Martin Hamer, Chicago, Ill., and Russell H. Brown, Hammond, Ind., assignors to Standard Oil Company, Chicago, Ill., a corporation of Indiana No Drawing. Filed Mar. 3, 1958, Ser. No. 718,491 8 Claims. (6i. 44-56) This invention relates to motor fuel compositions and particularly to motor fuel compositions for spark-ignition internal combustion engines adapted to prevent engines stalling due to carburetor icing.

Engine stalling due to carburetor icing occurs most frequently under engine idling conditions and particularly under weather conditions of relatively high humidity and at a temperature below about 60 F. While this problem has been in existence for many years, it has of late become of increased importance because of recent engine design. Most post war cars are provided with automatic chokes and provide no means for manual operation of the throttle so that operators of such cars are no longer able to regulate idle speeds during warm-up periods to prevent stalling. Furthermore, the idle speed of automobiles equipped with automatic transmissions is rather critical during the warm-up period and the fastest idle rate which may be used is limited to avoid creeping. Another factor in carburetor icing is the high volatility of motor fuels now provided for present-day engines.

It has been established that the cause of engine stalling in cool humid weather is the formation of ice in the engine carburetor. On such-cool moist days, the gasoline evaporated in the carburetor produces a sufiicient refrigerating effect to condense and freeze the moisture present in the air entering the carburetor. Fuel vaporization in the carburetor under such conditions can cause a temperature drop'in the carburetor of up to 50 F. below that of the entering air; as a result, up to the time of complete engine and radiator warm-up, this drop in temperature causes formation of ice crystals in the carburetor. The maximum refrigeration of the type referred to takes place under conditions of light load operation. As cooling of the carburetor parts takes place, ice begins to form as soon as these parts are refrigerated to a temperature below about 30 F., so that, when the throttle is closed to the idle position, the ice forms, formed or forming in the carburetor, particularly that formed, on the throttle plate and the adjacent walls, closes the narrow air ports, thereby restricting the normal flow of the air to the engine, causing repeated engine stalling. While an engine stalled, because of carburetor icing, can be readily started because the ice formed melts almost immediately due to residual heat from the exhaust manifold, it is highly desired to avoid any stalling due to carburetor icing because of the attendant inconvenience. For example, stalling due to carburetor icing of a car, equipped with automatic transmission, frequently does not occur until the driver is ready to accelerate so that at this most inconvenient time it is necessary to shift the car to neutral, restart the engine and shift back into gear, all of which magnifies the inconvenience of frequent stalls.

It is an object of the present invention to provide a motor fuel for a spark-ignition internal combustion engine which will prevent carburetor icing. Another object of the invention is to provide gasoline for spark-ignition intern-a1 combustion engines which will prevent the accumulation of ice crystals on carburetor parts during idling speed and under conditions of light load operation. Still another object of the invention is to provide a hydrocarbon motor fuel composition for spark-ignition internal combustion engines which will prevent engine stalling due to carburetor icing. Other objects and advantages of the present invention will become apparent from the following description thereof.

In accordance with the present invention, the foregoing objects can be attained by incorporating in the motor fuel for spark-ignition combustion engines from about 0.002% to about 0.05% of a substituted imidazoline salt, more fully defined hereinafter, and in combination therewith from about 0.01% to about 3.0% of an alkanol having from 1 to about 4 carbon atoms, such as methanol, ethanol, isopropanol, propanol, l-butanol, Z-butanol, 2- methyl-Z-propanol and isobutanol.

The substituted imidazoline salt used in this invention can be represented by the following probable general structure:

(i )1: RO(2) (4)0112 (1) (5) A( )m N CH2 (3112011221 (I) in which R is an alkyl, alkenyl or alkadienyl group or mixtures thereof, having from about 10 to about 24 carbon atoms, X is a polar group such as hydroxy, amino, carboxyl or an alkyl group containing one of such polar group, A is an anion of an aliphatic or cycloaliphatic carboxylic acid having from about 10 to about 60 carbon atoms, and n and m are integers 1, 2, or 3.

The imidazolines (or glyoxalidine) employed as starting materials are made by well known methods such as described in Wilson U.S. No. 2,267,965 and Wilkes U.S. No. 2,214,152. Briefly, the method involves reacting a fatty acid with an aliphatic polyamine with the elimination of water.

Specific examples of imidazolines suitable for use in the present invention include l-hydroxyethyl-2-heptadecenyl imidazoline, l-aminoethyl-Z-undecyl imidazoline, l-hydroxyethyl-2-pentadecyl imidazoline, l-aminoethyl-Z-heptadecenyl imidazoline, l-aminoethyl-Z-heptadecyl imidazoline, 1-hydroxyethyl-2 heptadecyl imidazoline, 1-a1'nino ethylethylamino-Z-heptadecenyl imidazoline, and the like.

Several commercial imidazoline compounds are avail- .able which can be used in the preparation of the above salts. Examples of such commercial products are Amine 0, Amine 220, and Nalcamine G 12, all of which contain R groups (above structure) of 17 carbon atoms and a hydroxyl polar group (X in the above structure). Another commercial imidazoline is Nalcamine G-39M which has the same R group but contains NHg'll'l its polar side group (X).

The carboxylic acid used in the formation of the substituted imidazoline salt can be any monomeric, dimer-ic or polymeric aliphatic or cycloaliphatic car-boxy-lic acid such as for example, oleic acid, stearic acid, tall oil acids, naphthenic acids, linoleic acid and polymeric linoleic'acids such as the dimer acids, trimer acids and higher polymeric acids or mixtures of such polymeric acids.

The preferred carboxylic acids used are organic aliphatic dicarboxylic acids produced by the condensation of two like or unlike molecules of a polyethenoid'monocarboxylic fatty 'acid, to give a product which is essentially a dimer, with minor amounts of monomers and trimers.

In general, the dimeric acids of this invention are produced by the condensation of two like or unlike unsaturated aliphatic monocarb'oxylic acidshaving between about 16 and about 18 carbon-atoms-per molecule. The dimeric acids are characterized by having the two carboxylic acid groups attached to a single six-membered hydroarorn'atic ring through la plurality of (CH groups the number of suchgroups being dependent upon the number of such groupsbetween the carbon atom of the carboxylic acid group and the nearer carbon of the nearest double bond of the monocarboxylic acid. The substituents are alkyl or alkenyl groups depending upon the degree of unsaturation of the monocarboxylic acid from which the dimeric acid is derived. Thus, the dimeric acids derived from a diethanoid fatty acid, or a dienoic acid have a single six-membered hydroaromatic ring substituted in two immediately adjacent positions by two alkyl groups and in two other immediately adjacent positions by carboxylic acid groups separated from the hydroaromatic ring in :one substituent by a straight chain unsaturated aliphatic group and in the other by a straight chain saturated aliphatic group. Consequently, the dimeric acids when prepared from the individual m-onocarboxylic acid are represented by two formulae Iii (II) where R is CH (CH and R is -(CH COOH and n is a small number one more than the number of CH groups between the terminal CH group and the nearer carbon of the nearer double bond of the diethanoid monocarboxylic acid from which the dimeric acid is derived and m is a small number representing the number of CH groups between the carbon of the carboxylic group and the nearer carbon of the nearer double bond of the diethenoid monocarboxylic acid from which the dimeric acid is derived, and

where R" is CII (CH and R is -(CH COOH and n and m have the same significance as before. The dimeric acids are dicarboxylic acids derived from two molecules of polyethenoid fatty acids of drying and semidrying oils and from fatty acids such as ricinoleic acid which upon dehydration become polyethenoid fatty acids. Therefore, in general, dimeric acids are dicarboxylic acids derived by the condensation of two molecules of one or more polyethenoid aliphatic monocarboxylic acids.

While the dimeric acids can be used in pure form, for practical reasons impure forms are used. That is to say, the dimeric acids are not presently available at commercially attractive costs in pure form.

A useful, commercially available dimeric carboxylic acid is commercially available under the trade name Emery 955-Dimer Acid. Since the commercial product is produced by dimerization of linoleic acid, it is usually referred to as dilinoleic acid. The commercial acid typically contains about 85% of dilinoleic acid, about 12% of trilinoleic acid and about 3% of monomeric acid.

Typical specifications for the commercial product are as follows:

Refractive index at 25 C 4 Specific gravity at 15.5 C./15.5 C 0.95 Flash point, F 530 Fire point, F 600 Viscosity at 25 C. (Gardner-Holdt) Z4 Viscosity at 25 C., centistokes 10,000 Viscosity at C., centistokes 100 Another satisfactory polymer acid is commercially available under the trade name of D-SO Acid. A similar product is marketed under the trade name VR-l Acids. Such acids may be produced as by-product stillresidues in the manufacture of sebacic acid by the distillation of castor oil in the presence of caustic. A method of obtaining such byproduct still-residues in the preparation of sebacic acid is described in US. 2,470,849, issued to W. E. Hanson, May 24, 1949. The mixture of high molecular weight unsaturated fatty acids comprises monomers, dimers, trimers and higher polymers in the ratio of from about 45% to about 55% of a monomers and dimers fraction having a molecular weight in the range of from about 300 to 600, and from about 45% to about 55% of a trimers and higher polymer fraction having a molecular weight in excess of 600. The fatty acid polymers result in part from a thermal polymerization of fatty acid type constituents of the castor oil, and in part from other reactions, such as the inter-molecular esterification, of such acid to form high molecular weight products. The acid mixture, which is mainly a mixture :of polymeric long chain polybasic carboxylic acids, is further characterized by the following specifications:

Acid No to 164 Saponification No to 186 Free fatty acids 75 to 82% Iodine value 44 to 55 The trim'eric acid which is the major constituent of the above described acids has the following probable formula:

HOO-(GHa)1-CH fiC-(GHaM-F-OH /OE CH CH- CH C a 2)u H Trimer Acid The imidazoline salts of the type herein-above described can be readily prepared by mixing the selected imidazoline and the carboxylic acid of the type described herein in mol ratios of 1:1 to 2:1, respectively and warming the reaction mixture at a temperature of from about 80 F. to 120 F., with or without a suitable catalyst, until a homogeneous product is obtained.

The preparation of illustrative imidazoline salts is demonstrated by the following examples:

EXA Vl PLE I continued an additional minutes to insure complete EXAMPLE II The salt of the above D-SO Acid and l-aminoethyl- Z-heptade-cenyl imidazoline was prepared by reacting molar ratios of the two reactants as in Example I.

The de-icer combination of the present invention can be usedin any hydrocarbon motor fuel in the gasoline boiling range adapted for use in automobile and aviation spark-ignition internal combustion engines. Such hydrocarbon motor fuels adapted to be used in the fall or spring (intermediate) and in the winter months when stalling due to carburetor icing is most prevalent, have an ASTM initial boiling point of about 90-80 F., a 90%-olf distillation temperature of not more than about 365-35 6 F. respectively and an end point of not more than about 415 F. Typical gasoline inspections are illustrated by the following:

The hydrocarbon motor fuel can contain any of the commonly used additives such as lead alkyl anti-knock agents, e.g. tetraethyl lead, lead scavenging agents, dyes, gum inhibitors, oxidation inhibitors, corrosion inhibitors, spark-plug fouling inhibitors, etc.

The effectiveness of de-icers in preventing engine stalls is determined in a single cylinder Lauson H2 engine equipped with a downdraft carburetor operated under the following conditions: Air from a CPR ice tower, and having a dry bulb temperature of 3740 F. and a wet bulb temperature of 3437 F. is fed to the carburetor of the engine operating on a test cycle of five minutes at full throttle, 1800 r.p.m., and five minutes at idle, 1800 r.p.m. This test cycle is repeated until the engine stalls.

Using, as the base fuel, a winter grade leaded gasoline containing a commercial antioxidant, and spark-plug fouling inhibitor, and having the following ASTM distillation characteristics:

Initial boiling point 80 10% recovery 106 50% recovery 191 90% recovery 302 End point 376 the following samples were subjected to the above de-icer test.

1 Volume percent.

The results obtained are tabulated in Table I.

Table I Percent Im- Sample No. Minutes to provement Stall Over Base Fuel The above data demonstrate the marked superiority of the combination of the substituted imidazoline salt and alkanol (sample 5) as a de-icer over other known compounds (samples No. 2, 3, 6 and 7) used as de-icers.

The de-ioing effectiveness of the combination of the present invention is further demonstrated by the results obtained in the operation of automobile engines operated in specially-instrumentedcold moms. In the cold room tests two engines are employed; a 1957-eight cylinder Buick engine and a 1954-six cylinder Plymouth engine. The engines are operated with intake air temperatures of 35-40 F. and humidity with continuous air circulation. The engines are started coldand accelerated to 1500 r.p.m. and maintained at said speed for one minute. The engine is then decelerated to idle rpm. and idled for one-half minute. Engine stalling and/or bucking characteristics are observed and recorded. If the engine stalls, it is immediately restarted and run through the described cycle.

The following gasoline compositions were subjected to the above test.

Sample 1: Control-same as above control Sample 2: Control+0.50% isopropanol +0.15% methanol Sample 3: Control+0.025% glyceryl mono oleate +0.15 methanol Sample 4: Control+0.025 dimethy1f0rmamide +015 methanol Sample 5 Control+0.002% linoleic acid dimer salt of 1- hydrroxyethyl-Z-heptadecenyl imidazoline Sample 6: Sample S t-0.15% methanol The results obtained in the above stalls-bucks test are given in Table II.

Table II Performance Sample No.

Buick Plymouth Stalls Bucks Stalls Bucks The effectiveness of the de-icer of the present invention is further demonstrated by the above data.

Percentages given herein are volume percentages, unless otherwise stated.

While the present invention has been illustrated by ref erence to preferred embodiments thereof, the invention is not to be limited thereby, but includes within its scope such modifications and variations as come within the spirit of the appended claims.

We claim:

1. A hydrocarbon motor fuel composition for sparkignition internal combustion engines to render said engines non-stalling due to carburetor icing comprising (A) a major amount of a hydrocarbon distillate in the gasoline distillation range; (B) from about 0.002 to about 0.05 of a hydroxyl-substituted imidazoline salt having the structural formula 1 CHzCHzOH in which R is a hydrocarbon radical having from about 10 to about 24 carbon atoms of the group consisting of alkyl, alkenyl, and lalkadienyl radicals, A is an anion of an organic carboxylic acid having from about 10 to about 60 carbon atoms in a hydrocarbon structure of the group consisting of an aliphatic carboxylic acid, a cycloaliphatic carboxylic acid, and mixtures of such acids, and n and m are integers of the group consisting of 1, 2 and 3; and (C) from about 0.01 to about 3.0% of a C alkanol.

2. A hydrocarbon motor fuel composition as described in claim 1 in which n and m are each 1, and R is an alkenyl radical.

3. A hydrocarbon motor fuel composition as described in claim 1 in which n and m are each 1, and R is an alkyl radical.

4. A hydrocarbon motor fuel composition as described in claim 1 in which A is the anion of polymerized linoleic acid.

5. A hydrocarbon motor fuel composition as described in claim 1 in which A is the anion of dilinoleic acid.

6. A hydrocarbon motor fuel composition as described in claim 1 in which the alkanol is methanol.

7. A hydrocarbon motor fuel composition for sparkignition internal combustion engines to render said engines non-stalling due to carburetor icing comprising (A) a major amount of a hydrocarbon distillate in the gasoline dsti'llation range; (B) fnom about 0.002 to about 0.05% of a dilinoleic acid salt of 1-hydroxyethyl-Z-heptadecenyl irnidazoline; and (C) from about 0.01 to about 015% methanol.

8. The method of preventing the stalling of spark-ignition internal combustion engines due to carburetor icing in moist cool temperature conditions which comprises burning in said engine a hydrocarbon motor fuel composi- 20 tion of claim 1.

References Cited in the file of this patent UNITED STATES PATENTS Petroleum Refining With Chemicals, by Kalichevsky and Kobe, Elsevier Publishing Co, 1956, page 480.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N0. 3,098,727 July 23, 1963 Martin Hamer et al.

that error appears in the above numbered pat- It is hereby certified e said Letters Patent should read as ent reqliring correction and that th corrected below.

Column 2, line 69, for "(CH read (CH Signed and sealed this 14th day of January 1964.

(SEAL) Attest:

ERNEST W. SWIDER EDWIN L. REYNOLDS Attesting Officer Ac Ling Commissioner of Patents 

1. A HYDROCARBON MOTOR FLUEL COMPOSITION FOR SPARKIGNITION INTERNAL COMBUSTION ENGINES TO RENDER SAID ENGINES NON-STALLING DUE TO CARBURETOR ICING COMPRISING (A) A MAJOR AMOUNT OF A HYDROCARBON DISTILLATE IN THE GASOLINE DISTILLATION RANGE; (B) FROM ABOUT 0.002 TO ABOUT 0.05% OF A HYDROXYL-SUBSTITUTED IMIDAZOLINE SALT HAVING THE STRUCTURAL FORMULA 